1. Field of the Invention
The present invention relates to an imaging apparatus for capturing an image of a subject and to a method for controlling the imaging apparatus.
2. Description of the Related Art
An optical coherence tomography (OCT) technique using interference of multi-wavelength light enables acquisition of a high-resolution tomographic image of a sample (in particular, a fundus of the eye).
In recent years, an ophthalmologic OCT apparatus can acquire, in addition to a normal OCT image of a shape of a fundus tissue, a polarization-sensitive OCT image using a polarization parameter (i.e., retardation and orientation), which is an optical characteristic of the fundus tissue.
The polarization-sensitive OCT (PS-OCT) can form the polarization-sensitive OCT image using the polarization parameter to be formed, and perform distinguishing and segmentation of the fundus tissue. PS-OCT uses the fact that some layers in the retina (or fundus) of an eye reflect polarized light differently from other layers. International Publication No. WO 2010/122118 A1 discusses a polarization-sensitive OCT which employs a light beam that has been modulated to a circularly-polarized beam as a measuring beam for examining the sample. Detection is then performed by splitting the interference beam into two linearly-polarized beams perpendicular to each other, so that the polarization-sensitive OCT image is generated with different layers in the fundus being imaged differently depending on their interaction with the polarized light.
It is desirable for a user to perform various adjustments (e.g., focusing) using a planar image of the subject, which the user is accustomed to seeing (e.g., a fundus image of the subject's eye acquired by a conventional SLO optical system), before acquiring the polarization-sensitive OCT image.